The present invention relates to an internal combustion engine of variable displacement.
The variable displacement is accomplished by varying the length of piston stroke, which in turn is accomplished by controllably varying the expulsion of work fluid driven by the piston.
A free piston is reciprocal in a cylinder between a combustion chamber and a fluid filled work chamber. The work chamber has a work output port expelling fluid during a power stroke of the piston. A fluid motor is operatively coupled to the work chamber and is driven by fluid from the work output port. A high speed valve between the work chamber and the fluid motor is selectively actuatable during the power stroke of the piston to stop expulsion of fluid from the work output port to the fluid motor to halt movement of the piston during the power stroke, since the fluid cannot escape. This provides variable displacement of the piston according to the relative timing of valve actuation during the power stroke. The variable length power stroke of the pistion provides a variable displacement of fluid to the fluid motor in proportion thereto. This further facilitates feedback control wherein the fuel supplied to the combustion chamber may be coordinated with the variable length power stroke of the piston as selectively controlled by the high speed valve, to afford a variable displacement engine with matching supplied fuel and power stroke. As the length of the power stroke decreases, the amount of fuel supplied to the combustion chamber may be decreased, and the amount of fluid expelled through the work output port to the fluid motor decreases.